# 回文数：首尾数字相等，对称。例：12321
def main_1(string: str):
    s = string[::-1]
    if s == string:
        return True


if __name__ == "__main__":
    string = "abcba"
    if main_1(string):
        print(f"{string}是回文串")
    else:
        print(f"{string}不是回文串")
